Many telecommunications applications require the creation and management of a session, where a session is considered an exchange of data between associated communication devices, such as computers and telephones. Some telecommunications sessions, for example telephone calls, are created, modified and terminated using a Session Initiation Protocol (SIP). SIP uses network hosts (called proxy servers) to which communication devices can send registrations, invitations to sessions, and other requests. In particular, the proxy servers help to, among other things, route requests to a current location of a communication device, authenticate and authorize communication devices for services, and implement provider call-routing policies.
To establish a communications session between a calling communication device and a called communication device, an SIP INVITE request is sent from the calling communication device to an associated proxy server. If the called communication device is also associated with the proxy server, the proxy server forwards the SIP INVITE request to the called communication device. If the called communication device is associated with another proxy server, the proxy server associated with the calling communication device forwards the SIP INVITE request to the called communication device through the other proxy server. The called communication device may thereafter respond to the SIP INVITE request by transmitting a response through the proxy server(s). The communications session between the calling communication device and the called communication device is established according to the SIP INVITE request and response from the calling communication device and the called communication device.
At a time when a session is being established with a first calling communication device and a called communication device, the called communication device will not be able to process a second request. For example, while the session is being established between the first calling communication device and the called communication device, if a SIP INVITE request is sent from a second calling communication device, the SIP INVITE request from the second calling communication device will be sent to, for example, a voice mail server associated with the called communication device or the proxy server may return a busy signal to the second calling communication device. As such, the called communication device is locked into addressing the first of multiple, simultaneous incoming calls. Therefore, when the called communication device is establishing a communication session with one calling communication device, a user of the called communication device is unaware of other potentially more urgent or important simultaneous incoming calls.
To make the user of the called communication device aware of multiple incoming calls, the existing SIP stack may be modified to handle multiple incoming calls simultaneously. However, this is resource intensive as each modified SIP INVITE request includes a Session Description Payload (SDP). The SIP user agent hardware will therefore have to handle a SDP for each simultaneous request. The user may also be made aware of multiple incoming calls if multiple telephone extensions are provided in a single communication device. Each incoming call may then be sent to a different extension on the communication device. This is also resource intensive as it requires additional telephony numbering resources.
Accordingly, there is a need for a method and apparatus for enabling the selection at least one of multiple, simultaneous incoming calls, on a called communication device without requiring extensive use of additional resources.
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The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.